For many visitors to central London hotels, purchasing an Oyster Card and topping it up with credit is a much easier and often cheaper way of getting around the capital than buying individual tube, train and bus tickets.
And Transport for London (TfL) will no doubt be selling a lot more of the cards in the run-up to the 2012 Olympics when sports fans from around the world are expected to descend on the city to take in all the action.
But while the current ones are pretty uninspiring in their design, tourists exploring London will now be able to buy some much more colourful Oyster Cards to brighten up their journeys from one landmark to another.
To celebrate the many major events taking place in the capital this year, TfL is launching a limited edition commemorative card depicting key London sights and events, including the Olympics, Paralympics and the Queen's Diamond Jubilee.
Around 1.5 million will be available to buy from London Underground stations, as well as travel information centres and shops selling Oyster Cards, tickets and top-ups. They can also be purchased online for those who'd like to buy their special edition cards ahead of time.
Of course once they've been used the cards will make great souvenirs for anyone who has visited the city during this exciting year.
Shashi Verma, director of customer experience at TfL, said: "This will be one of the most memorable summers that Londoners and visitors to the capital will experience and we are delighted to reflect that with our latest limited edition summer Oyster Cards.
"Our network will play a crucial role in delivering a wonderful summer and will provide many with a great souvenir as well as providing them with a convenient way to get around on public transport."
Oyster Cards were first introduced in London in 2003 and since then more than 43 million have been issued to residents, commuters and tourists.